A stroke occurs when the blood flow to a part of the brain is interrupted. The symptoms and severity of the stroke depend on the location and the extent of the stoppage because brain cells may be damaged or destroyed from lack of blood and oxygen.

Strokes may be ischemic, meaning that the blood flow is blocked from clots or clogged arteries, or hemorrhagic, which occurs when a blood vessel weakens, ruptures, and leaks into the surrounding tissue. Strokes occur for a variety of reasons, especially high blood pressure.

A recent study reviewed the effects of dietary magnesium on the risk of stroke with some encouraging findings. Researchers reviewed the results from seven prospective studies conducted between 1998 and 2011, which totaled 241,378 participants. Four of the studies were conducted in the U.S, two in Europe, and one in Taiwan. In all the studies, the dietary magnesium intake of the participants was recorded and divided into comparison groups ranging from highest to lowest intake.

All seven studies were controlled for age, smoking, and BMI. Most of the studies were also controlled for activity level, diabetes, alcohol intake, and hypertension. The groups were followed to see who developed strokes. There were 6,477 cases of stroke among all the study participants.

The median magnesium intake in the study groups ranged from 242 mg/d to 471 mg/d. (The recommended U.S. dietary allowance for men 31 years and older is 420 mg/day). People with magnesium deficiency may show signs of agitation and anxiety, sleep disorders, and abnormal heart rhythms, among other symptoms.

There was a significant inverse relationship between dietary magnesium intake and the risk of stroke. The higher the magnesium intake, the lower the stroke risk. An increase in intake of 100 mg/d was associated with an eight to nine percent decreased risk of ischemic, but not hemorraghic stroke.

Dietary magnesium has been shown to have a positive impact on decreasing hypertension, metabolic syndrome, and type 2 diabetes in humans. Animal studies have shown that high magnesium diets have a positive effect on the levels of glucose and lipids in the blood. Since all of these conditions are risk factors for stroke, the researchers suggest that this may explain why magnesium reduces the risk of stroke.

The study was done on dietary magnesium, not supplements. The researchers maintain that people should improve their magnesium intake through nutritional sources, and state that it is premature to recommend magnesium supplements based on current data.

Foods rich in magnesium include green leafy vegetables such as spinach (78 mg.1/2 cup), beans (74 mg/1/2 cup soybeans), nuts (50 mg/ounce peanuts), and whole grains (77 mg/cup raisin bran cereal). The recommended dietary allowance of magnesium adult males 31 years and older is 420 mg/day and 320 mg/day for females. There are different recommendations for other age groups as well as for pregnant and lactating women.